Magnesium oxide boosts serum magnesium levels in functional constipation

Daily treatment with magnesium oxide increases serum magnesium levels in children with functional constipation but not to a critical extent, a new study indicates.

Magnesium-containing cathartics are commonly prescribed to treat chronic constipation. Hypermagnesemia is rare, but serious complications, even deaths, have been reported in adults treated with magnesium oxide, and monitoring of magnesium concentrations in regular users is recommended.

Children with functional constipation may take magnesium-containing cathartics for long periods, so it is important for pediatricians to know whether hypermagnesemia can develop in children with normal renal function who take these agents daily.

Among constipated children, the median serum magnesium concentration was significantly higher than in the control group (2.4 mg/dL vs 2.2 mg/dL). None of the patients reached the critical limit of serum magnesium concentration (4.3 mg/dL) or experienced symptoms of hypermagnesemia. Renal magnesium clearance was significantly elevated in constipated children compared with controls.

Serum magnesium levels decreased significantly with age in the constipated group but not in the control group. No significant correlation was found between serum magnesium levels and duration or daily dose of magnesium treatment.

Younger age but not prolonged daily use of magnesium oxide may be a relative risk factor for hypermagnesemia.

Tatsuki M, Miyazawa R, Tomomasa T, Ishige T, Nakazawa T, Arakawa H. Serum magnesium concentration in children with functional constipation treated with magnesium oxide. World J Gastroenterol. 2011;17(6):779-783.